Unseemly dent nice when repaired (8)
I believe the answer is:
indecent
'unseemly' is the definition.
(I know that unseemly can be written as indecent)
'dent nice when repaired' is the wordplay.
'when repaired' is an anagram indicator (I've seen this in other clues).
'dent'+'nice'='dentnice'
'dentnice' is an anagram of 'INDECENT'.
(Other definitions for indecent that I've seen before include "Gross, unbecoming" , "Indecorous" , "Gross, obscene" , "Vulgar" , "Smutty" .)